title: Does the peritumoral stroma of basal cell carcinoma recapitulate the follicular connective tissue sheath?
abstract: BACKGROUND
  There are compelling embryologic and anatomic relationships within adnexal tumors. However, these are mostly perceived within the epithelial component while the stromal component of the tumors is frequently overlooked. In postnatal skin, nestin is almost exclusively expressed in the perifollicular mesenchyme. This study examines the expression of this neuroepithelial stem cell protein in trichoblastoma/trichoepithelioma and in basal cell carcinoma (BCC), which is increasingly being viewed as follicular in nature.
  
  
  METHODS
  We employed standard immunohistochemical methods with three different antibodies to examine the expression of nestin in 25 BCCs and compared the staining pattern with that of 7 trichoblastomas and 11 trichoepitheliomas.
  
  
  RESULTS
  Nestin is expressed in the peritumoral stroma of all tumors examined and is limited to the immediate layer of mesenchymal cells surrounding the tumor epithelium. In BCC, nestin-immunoreactive cells are found as a sheath of thin, spindled fibroblasts, while reactive cells are plump in trichoepitheliomas/trichoblastomas.
  
  
  CONCLUSIONS
  We postulate that the peritumoral stroma of BCC imitates the perifollicular connective tissue sheath, while in contrast that of trichoepithelioma/trichoblastoma is similar to the papillary and immediate peripapillary follicular mesenchyme. Further functional and animal experimental studies are needed to test this hypothesis.
authors.affiliation: Department of Dermatology, Cleveland Clinic Foundation, Cleveland, OH, USA. klaus.sellheyer@gmail.com
authors.forename: Klaus
authors.initials: K
authors.lastname: Sellheyer
authors.forename: Dieter
authors.initials: D
authors.lastname: Krahl
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis / Q000378:metabolism; D002280:Basal Cell Carcinoma / Q000378:metabolism* / Q000473:pathology*; D003238:Connective Tissue / Q000378:metabolism / Q000473:pathology; D018859:Hair Follicle / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000096:biosynthesis; D018294:Neoplasms, Adnexal and Skin Appendage / Q000378:metabolism / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D064231:Nestin; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology*; D059016:Tumor Microenvironment
chemical_list: D014408:Biomarkers, Tumor; D007381:Intermediate Filament Proteins; C577484:NES protein, human; D009419:Nerve Tissue Proteins; D064231:Nestin